[Urothelium-dependent modulation of urinary bladder smooth muscle contractions by menthol].

TRPM8 cold receptor/channel is considered amongst the variety of receptors that support and modulate sensory function of urothelium, although the information regarding this is still quite contradictory. Here we have studied the effects of nonspecific TRPM8 activator menthol on the contractions of the smooth muscle strips of the rat bladder with intact and removed urothelium, and assessed the expression in them of TRPM8 mRNA using semi-quantitative RT-PCR. Menthol (100 microM) decreased the basal tone and the amplitude of spontaneous contractions only in the strips with intact urothelium.

[A hyperpolarization-activated current in rat menthol-sensitive sensory neurons].

In the present study we have investigated the correlation between hyperpolarization-activated current (1(h)) and menthol-activated current (I(TRPM8)) in rat dorsal root ganglion (DRG) neurons. We showed that I(h) is present in 89% of menthol-sensitive neurons which makes its presence reliable, though not absolute, criterion for pre-selection of such neurons. Endogenous I(h) recorded from different neurons exhibited variable density and activation kinetics.

[Testosterone modulation of HERG potassium channel blockade induced by neuroleptics].

The repolarisation phase of cardiac action potential is characterized by sexual dimorphism suggesting the role of sex steroid hormones in the regulation of K+ channels. Here we report on the effect of testosterone on blockade of HERG-encoded K+ channels induced by neuroleptics. These compounds are used in clinics to treat psychiatric disorders, but reportedly have proarrhythmic side effects, on HERG-encoded K+ channels responsible for the rapid component of cardiac delayed rectifier K+ current, IKr.

[Effects of sex hormones on HERG potassium channels expressed in Xenopus oocytes].

The repolarisation phase of cardiac action potential is characterized by sexual dimorphism suggesting the role of sex steroid hormones in the regulation of K+ channels. Here we report on the effects of testosterone and 17 beta-estradiol on HERG-encoded K+ channels, expressed in Xenopus oocytes. At 1M concentration testosterone decreased the amplitude of HERG-directed IKr (rapid component of cardiac delayed rectifier K+ current) by 30% within 30 min of exposure, while 17-estradiol had no effect.

[Blockade of HERG K+ channels expressed in Xenopus oocytes by antipsychotic agents].

We have investigated the effects of neuroleptic agents, haloperidol, pimozide and fluspirilen, that are used in clinics to treat psychiatric disorders, but reportedly have proarrhythmic side effects, on HERG-encoded K+ channels responsible for the rapid component of cardiac delayed rectifier K+ current, IKr. All three agents blocked HERG-directed IKr in Xenopus oocytes in a voltage-dependent manner. The extent of the blockade increased with depolarization correlating with channels activation consistent with open-channel blocking mechanism.